Bolt

ABSTRACT

A bolt ( 10 ) for securing timber to any other material, comprises: a bolt head ( 101 ) with a series of spiked teeth ( 102 ) on its underside; a cylindrical bolt rod ( 103 ) extending from the bolt head ( 101 ) is threaded and split into two rods ( 105   a,b ) at its free end, so as to define a slot ( 106 ) therebetween. In use a user drills a hole through pieces of timber to be secured together, and hammers the bolt through the hole. The spiked teeth on the bolt head lock into the timber, securing the bolt at one end. At the free, split end of the bolt rod, a washer and nut are tightened onto the bolt. A cold chisel is hammered into the slot between the split ends of the rod, bending the ends outwards and thus preventing the nut from loosening.

FIELD OF THE INVENTION

The present invention relates to an engineered bolt and moreparticularly, but not exclusively, the invention relates to anengineered bolt for securing pieces of timber together or pieces oftimber to other materials.

BACKGROUND OF THE INVENTION

Often, those working in the construction industry, such as builders andcarpenters, need to construct prefabricated items or structures fromwood or timber. Pieces of wood or timber forming such items orstructures were often secured one to another using fixings such asnails, screws or bolts.

Whilst screws and nails were useful for attaching small pieces of wood,one to another, the usual manner of securing larger pieces of timbertogether or securing timber to third party materials, for example of thesort used in frames and larger structures, involves drilling a holethrough each material where they should be joined. There are then twotraditional methods of securing the materials together:

Option 1—A metal bolt, usually made of steel, is passed through thehole, a nut and washer is then tighten onto the threaded end, soeffectively clamping the pieces of timber or timber to a third partymaterial together.

Option 2—A threaded rod is cut to the correct length to fit through thehole created, with a small excess on either side. A washer and a nut aretightened onto each end, holding the pieces of timber together, soeffectively clamping the pieces of timber or third party materialtogether.

These bolts/threaded rods were typically of a diameter between 8 mm and20 mm.

Although this method was widely used, it suffered from severaldisadvantages.

The use of a ‘coach bolt’ in securing timber members has many drawbacksand limitations, namely:

-   -   1. It relies on the user to drill the correctly sized hole        through the timber members. Due to the small head size in        relation to the diameter size of the bolt, there is little        tolerance for drilling an over-sized hole.    -   2. Due to the small surface area of the head to the bolt, it is        usual for Building

Control Officers to request the use of a 50 mm×50 mm washer.

-   -   3. It is a common occurrence for the bolt to turn within the        timber before it is completely tight or has reached the correct        torque.    -   4. It is also a common occurrence for the small head of the bolt        to be pulled into the timber member, deforming the timber face,        thereby reducing the effective structural depth of the timber as        designed.    -   5. In the case of domed headed bolts the bolt makes it difficult        to subsequently attach or fix finishing materials, such a        plywood and plasterboard, as it is not possible to achieve a        true level surface without remedial works being required.    -   6. There are instances which require the contractor to pass the        bolt through the first member and then offer up the second        member over the bolt. The second member pushes the bolt out of        the first member adding to the frustration.    -   7. Due to the small surface area of the head to the bolt, it is        difficult to achieve the correct torque to the nut without        deforming the surface of the timber member. This is a particular        issue when the head of the bolt is visible. It leads to an        unsightly finish.    -   8. There is no facility to restrain the bolt in position.

The use of threaded rod in securing timber members also has manydrawbacks and limitations, namely:

-   -   1. Wastage is excessive and common due to the bars being        supplied in set lengths. It is exceptionally unusual to use the        entire rod.    -   2. When the rod has been cut, the thread becomes deformed making        it difficult to thread the nuts.    -   3. In order to fix the rod in position, it requires two sets of        nuts and two sets 50 mm×50 mm washers, which adds expense and is        often awkward.    -   4. It is a common occurrence that when tightening one nut, the        shaft or bar has a tendency to turn within the opposing nut,        thereby winding the rod through the timber members.    -   5. There is no facility to restrain the nut or threaded rod in        position.    -   6. It is an awkward and time-consuming activity for those        working in construction, as they must tighten one washer and nut        onto one side of the threaded rod, then hold it in place with a        spanner whilst tightening a washer and nut on the other side        resulting in continuous access being required. to both ends of        the bolt, using two separate spanners, in order to secure the        fixing. Space constraints commonly experienced on construction        sites often restrict the possibility of achieving this.    -   7. The nuts can become loose and may be lost, decreasing the        likelihood of the fabrication staying together and potentially        putting people at risk.

Means of securing pieces of timber and other construction materials thatrequire fewer parts are known in the art. For example, DE-A-3 133 638(Bergner Richard GmbH) discloses a screw device with a head comprising aseries of spiked teeth, which latch into the wooden material. However,the matter of the head of the bolt gouging into a work piece was notaddressed.

Although the bolt described in DE-A-3 133 638 was an improvement uponexisting methods, (because it required no nut or washer on one side ofthe work piece or building materials), the screw device disclosed madeno attempt to further secure both ends of the bolt. The result was thatdespite a washer and nut being placed on a ‘blind side’, the bolt couldstill work loose. Furthermore, in many jurisdictions, buildingregulations require the bolt to fully pass through the surface itpenetrated and to be secured by a nut. As such, in many situations, thescrew device does not always meet building regulation standards.

Another example of a screw device is disclosed in UK Patent GB-B-2 372304 (Rendell). A bolt with a hexagonal head is disclosed. The bolt hasspikes formed in the head of the bolt. The spikes engage a surface andimpede rotation of the bolt, for example when being tightened from ablind side of a work piece.

French Patent Application FR-A-997085 (Dehousse) discloses a bolt whichhas a notch formed at its end. This would not have been appropriate forjoining two timber work pieces.

The present invention arose in order to provide an improved bolt whichis quick and simple to install, cheap to manufacture and does not sufferfrom the aforementioned disadvantages of turning whilst being tightened,falling out of timber due fabrication, pulling through timber, workingloose over time, as well as providing a safer way of joining timberpieces together or a timber to another structure, without the risk ofbolts and nuts working loose.

SUMMARY OF THE INVENTION

According to a first aspect of the invention there is provided a bolthas a head and a shaft for receiving a nut, at least a portion of whichshaft is threaded, a notch is formed in a distal end of the shaft and atleast one engagement means is provided on an underside of the head ofthe bolt.

Therefore, in use, the invention ensures that the length of the boltthat is retained between the head and a washer and a nut is heldconstant. This is because the nut is locked at a specific location bythe action of urging distal ends of the shaft

The notch is advantageously formed symmetrically about the axis of theshaft. That is, in the case of a notch with parallel, planar opposingwalls, the mid-point of the notch (that is the point half way betweenthe opposing walls that define the notch), lies on the axis of theshaft.

Ideally the notch extends for a relatively short distance into theshaft. Typically the short distance to which the shaft extends is lessthan 20 mm, ideally less than 10 mm, preferably less than 8 mm and mostpreferably less than 5 mm.

The width of the notch is more than 1 mm and preferably less than 3 mm.

The notch may be formed with the shaft, for example by way of a forgingor pressing stage or it can be formed by a sawing, cutting or punchingprocess.

The axis of the notch is ideally parallel to the longitudinal axis ofthe shaft and ideally the side walls, defining the notch aresubstantially parallel. However, other shapes and types of notches maybe formed, which do not have parallel walls. These include notches thatare tapered inwards or outwards from the axis of the shaft; notches thatare twisted (that is spiral) or curved; notches that have non-planarinner walls, for example notches that have a cylindrical inner surface;and notches that have saw-tooth or other surface profiles.

Advantageously the head of the bolt is shaped and dimensioned to bereceived by a spanner or similar means for applying torque. Ideallytherefore the head of the bolt is hexagonal or preferably square.However, in some embodiments the bolt head may be round or oval or someother shape.

Preferably the thickness of the head is less than 5 mm; preferably it isless than 2 mm thick. The reason why the head of the bolt should be asthin as possible is so that when it is pressed into a work piece andtightened by a nut, the head lies flush, or as flush as possible, withthe work piece, so presenting as flat a profile as possible. Anadvantage of this is that it allows subsequent sheets—such asplasterboard—to be placed over the head of the bolt. This was not thecase with previous coach bolts as they presented a large profile whichimpinged on overlaid boards.

Preferably at least one tooth or other engagement means is provided onan underside of the head of the bolt.

Ideally a plurality of teeth or other engagement means are provided onthe underside of the head of the bolt. Optionally these teeth or otherengagement means are formed integrally with the head of the bolt,although they may be attached thereto at a separate forming stage.

Preferably the, or each, tooth or engagement means is formed byselectively weakening or cutting suitably shaped portions from the bolthead and then folding or bending the cut, suitably shaped portions so asto define a scoop-shaped claw or tooth or engagement means.

Alternatively the, or each, engagement means is formed by pressing,casting, forging, punching or moulding suitably shaped portionsintegrally with the bolt head and arranging them so as to define ascoop-shaped claw or tooth.

An advantage with the scoop-shaped claw, tooth or other engagementmeans, is that it prevents the bolt, once in place, from loosening. Thisis because in use, the head of the bolt penetrates into the timber insuch a manner as to resist a torque that is applied to the shaft that isin the opposite sense to the direction of the scoop-shaped claw, toothor other engagement means. The engagement of the head of a bolt can beachieved by a minimal pressure of the bolt so as the scoop-shaped claw,teeth or other engagement means can engage with the work piece. This canbe achieved by hand or with a tool which may be a spanner or wrench orby application of a gentle tap by a hammer or mallet.

Unlike the previous embodiments the teeth or other engagement means,such as a scoop or spike or claw, do not simply grip a work piece andprevent rotation of the bolt. Instead they penetrate material to a depthof at least 2 mm, preferably at least 3 mm and most preferably 4 mm ormore with very large bolts, so as to provide optimum purchase. Becauseof the relatively large surface area of the teeth or other engagementmeans and their inherent material strength, once they have becomeembedded in the work piece, they are able to resist very large torquesthat may be transmitted to the shaft when the nut is tightened.

Ideally the teeth or other engagement means have sharp penetrating tipsand these are most preferably triangular or pyramid-shaped penetratingpoints.

It is therefore apparent that once tightened these teeth or otherengagement means engage with the work piece, they act as a grippingdevice and render the bolt secure against inadvertent loosening duringuse. The bolt performs optimally once the teeth or other engagementmeans of the bolt have penetrated to a minimum depth of around 3-5 mm.Because the head of the bolt presents a relatively large area thisensures that even if a user drills too large a hole for bolt, then thehead provides a sufficiently large footprint to engage with the surfaceof the work piece.

Ideally the head of the bolt has a surface area of at least 25×10⁻⁶ m,preferably the head of the bolt has a surface area of at least 49×10⁻⁶m, and most preferably the head of the bolt has a surface area of atleast 100×10⁻⁶ m. These areas correspond to lengths of a square headedbolt of 5 mm, 7 mm and 10 mm respectively. However, larger, squareheaded bolts, for example greater than 10 mm square, are also within thescope of this invention. For example the head of the bolt may be sizedso that it is at least 2 cm×2 cm square, preferably 3 cm×3 cm squaremost preferably 4 cm×4 cm, and, and possibly even larger in specificapplications.

Because the teeth of the bolt penetrate the material to a depth of atleast 5 mm, a substantial reactive force is presented to any torque thatis applied to a nut connected to the remote end of the bolt.

To this end, disclosed is a bolt for securing timber, comprising: a bolthead with a series of spiked teeth on its underside; a cylindrical boltrod extending from the bolt head comprising a thread and a splittinginto two rods at its free end, forming a slot between them.

In use, a carpenter or builder drills a hole through the pieces oftimber to be secured together, and places the bolt through the hole. Thespiked teeth on the bolt head are shaped and dimensioned to cut into thetimber and engage therewith, so securing the bolt at one end. At thefree end of the bolt, where the notch is formed, the shaft iseffectively split into two portions. A washer and nut are then placedonto the free end of the bolt and tightened onto it.

The user then urges the two split portions, defined by the notch, apartso they are slightly splayed. This may be achieved for example by gentlytapping a cold chisel into the slot between the split ends of the rod orbending the ends outwards, for example with a flat head screwdriver orother similar tool, thus preventing the nut from loosening because thediameter of the end of the shaft has been increased by a small amountsufficient to entrap the nut on the shaft and prevent it from unwinding.

It can be seen from the invention that a bolt is provided for securingpieces of timber together and that the bolt does not require separateparts; is easy to install and cannot simply loosen and fall out ofposition.

Another advantage of the present invention is that it secures pieces oftimber with fewer individual parts and in much less time. Therefore lessmaterial is used.

A yet further advantage is that the head of the bolt, once engaged witha work piece, does not turn whilst the nut is tightened.

Another advantage is that once the bolt is placed into position it doesnot fall out of the timber and is self-securing, so enabling a singleperson to erect buildings and structures easier than was previously thecase.

The invention will now be described, by way of example only and withreference to the following drawings, in which:

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a diagrammatical side elevation of an embodiment of theinvention with a rounded bolt head;

FIG. 2 shows a diagrammatical side elevation of an embodiment of theinvention with a flat, square bolt head;

FIG. 3 shows in diagrammatical form the bolt holding two pieces of woodtogether;

FIG. 4 is an overall view of a preferred embodiment of the invention;

FIGS. 5 a and 5 b show detailed views of the distal end of the bolt andhow a tool is used to split the ends of the bolt, when urged into theslot;

FIG. 6 are two graphs showing relative resistance to torque of boltsaccording to the invention when compared with existing bolts of similardimensions;

FIGS. 7 a to 7 c are plan, under plan and elevation views of a preferredembodiment of the invention;

FIGS. 8 a to 8 e show under plan and side elevation view of 5alternative embodiments of the invention; and

FIGS. 9 a to 9 j illustrate steps in a preferred method of forming thebolt.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT

Referring to the Figures generally and specifically FIGS. 1 and 2 whichshow a bolt 10, suitable for securing timber. Bolt 10 comprises a bolthead 101 with a series of spiked engagement means, in the form of teeth102 on its underside. A cylindrical bolt rod 103 extends from the bolthead 101. A portion of the shaft of the bolt rod 103 has a thread 104formed thereon. The end of the bolt rod 103 is split into two portions105 a and 105 b at its free end, defining a slot 106 between the twoportions 105 a and 105 b.

Bolt head 101 may be of any known bolt head form, for example, it may bea pan head, a domed head, a round head, a truss head or any other, butis ideally square shaped. The bolt head 101 includes a plurality ofspiked teeth 102 on its underside, which, in use, contact a work pieceto be secured. Spikes 102 are sufficiently sharp to pierce the timberand thus grip onto it.

FIG. 3 shows in diagrammatical form the bolt holding two pieces of woodA and B together. The cylindrical bolt rod 103 extends from the bolthead 101 and may be provided in any thickness or length as shown forexample in FIGS. 8 a to 8 e.

FIG. 4 shows an overall view of the bolt and illustrates how the thread104 extends along the cylindrical bolt rod 103. However, the thread 104may extend only part way along the entire rod 103 as appropriate. At thefree end of the rod 103, distal from the bolt head 101, the rod 103splits into two rod portions 105 a and 105 b forming a slot 106 inbetween them. The two rod portions 105 a and 105 b are of sufficientdimensions and strength so that they are adapted to bend and not breakor snap. This may be achieved by tapering them and/or by treating theportion of the bolt in a manner so as to render the material moreflexible than the remaining part of the bolt. The reason for the slot106 is explained with reference to FIGS. 5 a and 5 b, which show inexploded form views of the slot before (FIG. 5 a) a chisel or other tool201 is urged into the slot 106 and after (FIG. 5 a) a chisel or othertool 201 is urged into the slot 106 and has caused deformation of thetwo portions 105 a and 105 b.

The entire bolt is preferably formed from steel, but any other suitablematerial known in the art may be used. For example, bolts may be formedfrom an alloy, aluminum, chrome, brass or synthetic plastics materialsor a composite material. The bolt may be plated chrome or coated ininsulating or with a conductive material, such as gold. Bolts may begalvanized or powder coated. Bolts may be coloured in order todistinguish them from conventional bolts, so that for example a buildercan locate them, easily in a tray of similar bolts. Different coloursmay be used for different sized bolts—eg M10 may be red, M12 may be blueand M14 may be yellow or different colours may be used to distinguishdifferent size, or different shape, slots.

Referring briefly to FIGS. 3, 4 and 5, in use, a user (not shown) drillsa hole through two pieces of timber A and B to be secured together. Theuser forces bolt 10 through the two pieces of timber—eg by hand or byway of a hammer. Spiked teeth 102 on bolt head 101 lock into the timber,securing the bolt on one face of timber A. At the free, split end of thebolt rod 103, a washer 130 and nut 140 are tightened onto the bolt. Acold chisel (not shown) is then gently hammered into the slot 106between the split ends 105 a and 105 b of the bolt rod, bending the tipsof the ends 105 a and 105 b outwards, thus preventing the nut 140 fromloosening. This feature of the invention is particularly advantageousbecause the splayed ends 105 a and 105 b of the bolt prevent inadvertentremoval or loosening of the nut from the bolt and therefore importantlyensures that the length of the bolt that is retained between the head101 and the washer 130 is held constant. This is because the nut islocked at a specific location by the action of the splayed leg portions105 a and 105 b.

Referring briefly to FIG. 6 which shows two graphs that illustrate therelative resistance to torque of bolts according to the invention, whencompared with existing bolts of similar dimensions. It can be seen thatas a result of the teeth penetrate into the work piece, that torsionalloading is transmitted across a larger surface area—determined by thespacing of the teeth from the axis of the bolt shaft—and so a bolt isless likely to twist and cut its way into a work piece. The advantage ofthis that the length of the bolt that grips a work piece remainsconstant.

Brief reference will now be made to FIGS. 9 a to 9 j which illustrates amanufacturing method for forming the bolt 10. FIG. 9 a shows thebeginning of the process, commencing with blank wire 400. Typically thediameter of the wire 400 ranges from 8 mm to 20 mm. The wire is deformedusing a specialised apparatus that squashes the wire and cold forms ahead 402. FIG. 9 c shows an under plan view of the preformed bolt whichhas a key 406 shaped in the form of a hexagon.

FIG. 9 d shows how a thread is cut into the wire and a slot 106 isformed at its end. A key 406 is shaped and dimensioned to be received bya specially formed washer 408 b, which initially is in the form of asquare of steel 408 a (FIG. 9 e) which has an hexagonal shape cut fromit and tangs 410 punched in it to it and these are then foldeddownwards.

The tangs 410, shown in FIG. 9 g, define the plurality of spiked teeth102. They are angled in the same sense as the thread so that, when atorque is applied to the bolt, they twist into a work piece. The finalstage of the manufacturing process introduces the preform wire 400 intothe washer 408 b which is then pressed into the hexagonal locator 412.The locator ensures there is a good fit with the hexagon in the washer408 b. A circular collar 425, when deformed by a press (not shown)provides an annular fillet of material which is cold upset (in a mannersimilar to forming a rivet head) so that the material in the collar 425is folded over the hexagonal head 406 and so locks it in place in thekey defined in the washer 408 b.

The invention has been described by way of example only and it will beappreciated that variation may be made to the embodiments describedwithout departing from the scope of the invention. For example the headof the bolt can be shaped to receive an Allen key or other suitable toolfor applying torque to the head of the bolt.

1. A bolt has a head and a shaft for receiving a nut, at least a portionof which shaft is threaded, a notch is formed in a distal end of theshaft and at least one engagement means is provided on an underside ofthe head of the bolt.
 2. A bolt according to claim 1 wherein the notchis formed symmetrically about the axis of the shaft.
 3. A bolt accordingto claim 1 wherein the notch has parallel, planar opposing walls, themid-point of the notch (that is the point half way between the opposingwalls that define the notch), lies on the axis of the shaft.
 4. A boltaccording to claim 1 wherein the mid-point of the notch is coincidentwith the axis of the shaft.
 5. A bolt according to claim 1 wherein thewidth of the notch is less than 4 mm.
 6. A bolt according to claim 1wherein the notch has tapering walls.
 7. A bolt according to claim 1wherein the notch has walls that twist or spiral.
 8. A bolt according toclaim 1 wherein the notch has non-planar inner walls.
 9. A boltaccording to claim 1 wherein the notch has a cylindrical inner surfaceprofile.
 10. A bolt according to claim 1 wherein the notch has asaw-tooth inner surface profile.
 11. A bolt according to claim 1 whereinthe notch extends for a distance into the shaft, which is less than 20mm.
 12. A bolt according to claim 1 wherein the notch extends for adistance into the shaft, which is less than 10 mm.
 13. A bolt accordingto claim 1 wherein the notch extends for a distance into the shaft,which is less than 5 mm.
 14. A bolt according to claim 1 wherein thewidth of the notch is more than 1 mm.
 15. A bolt according to claim 1wherein the width of the notch is less than 5 mm.
 16. A bolt accordingto claim 1 wherein the notch is formed by a process from the groupcomprising: forging, pressing, sawing, cutting and punching.
 17. A boltaccording to claim 1 wherein the head of the bolt is shaped anddimensioned to be received by a spanner or similar means for applyingtorque.
 18. A bolt according to claim 17 wherein the head of the bolt issquare.
 19. A bolt according to claim 1 wherein the bolt head is roundor oval.
 20. A bolt according to claim 1 wherein the teeth or otherengagement means are formed integrally with the head of the bolt.
 21. Abolt according to claim 1 wherein the, or each, tooth or engagementmeans is formed by selectively weakening or cutting suitably shapedportions from the bolt head and then folding or bending the portions soas to define a scoop-shaped claw or tooth or engagement means.
 22. Abolt according to claim 1 wherein the, or each, tooth or engagementmeans is formed by pressing, casting, forging, punching or mouldingsuitably shaped portions integrally with the bolt head and arrangingthem so as to define a scoop-shaped claw or tooth.
 23. A bolt accordingto claim 1 wherein four teeth or other engagement means are provided,each located at the corner of a square.
 24. A bolt according to claim 1wherein the teeth or other engagement means is at least 2 mm so as toprovide optimum purchase.
 25. A bolt according to claim 20 wherein theteeth or other engagement means are at least 3 mm so as to provideoptimum purchase.
 26. A bolt according to claim 1 wherein the teeth orother engagement means are at least 4 mm longs, so as to provide optimumpurchase.
 27. A bolt according to claim 1 wherein the teeth or otherengagement means have sharp penetrating tips.
 28. A bolt according toclaim 27 wherein the teeth or other engagement means have triangular orpyramid-shaped penetrating points.
 29. A bolt according to claim 27wherein the teeth or other engagement means are located along edges ofthe head of the bolt.
 30. A bolt according to claim 27 wherein at leastone tooth is located at each edge of the head of the bolt.
 31. A boltaccording to claim 1 wherein the head of the bolt has a surface area ofat least 25×10⁻⁶ m.
 32. A bolt according to claim 29 wherein the head ofthe bolt has a surface area of at least 49×10⁻⁶ m.
 33. A bolt accordingto claim 29 wherein the head of the bolt has a surface area of at least100×10⁻⁶ m.
 34. A bolt according to claim 1 formed from steel.
 35. Abolt according to claim 34 plated with chrome.
 36. A bolt according toclaim 34 which is galvanized.
 37. A method of fabricating a boltaccording to claim 1 comprising the steps of: forging a bolt having ashaft and a head and forming a threaded portion around at least aportion of the shaft and forming a notch at a tip of the shaft.
 38. Amethod of fabricating a bolt according to claim 37 comprising the stepsof: forming at least one tooth under the head of the bolt so that, inuse, the at least one tooth engages with a piece of timber. 39-40.(canceled)